def solve():
    L, R = [int(s) for s in input().split()]

    if L == R == 0:
        print(0)
        return

    log_l, log_r = L.bit_length() - 1, R.bit_length() - 1

    if log_l < log_r:
        print((2**log_r) * (2**log_r - 1))
    else:
        print(-1)


if __name__ == "__main__":
    T = int(input())

    for _ in range(T):
        solve()